1. Field of the Invention
The present invention relates generally to the installation and maintenance of systems for distributing highly purified gases in controlled environments, such as integrated circuit manufacturing equipment. More particularly, it relates to an apparatus that will purify such distribution systems after their fabrication or maintenance procedures that introduce contamination to the gas distribution system.
2. Description of the Prior Art
The fabrication of integrated circuits requires the use of large quantities of purified gases, such as nitrogen, oxygen, hydrogen and helium that are as particle free as possible, used in a clean room or laminar flow hoods. The presence of contaminants, such as particulate matter or unwanted moisture in the gases will result in defective integrated circuits, either reducing yields of acceptable circuits or making it impossible to fabricate any circuits that meet specifications. In order to distribute the purified gases to an integrated circuit (IC) manufacturing equipment, a gas distribution system free of contaminants is required.
It is conventional practice in the industry to fabricate the components of the gas distribution system themselves in a clean room environment. However, when such components are assembled together to make the gas distribution system, working with pipes, including brazing or welding them, contaminates components which are initially free of contamination with particulate matter. Because it is impossible as a practical matter to carry out all of the gas distribution system assembly in a controlled environment, such as a glove box, unwanted moisture is also introduced into the gas distribution system. Particulate and moisture contamination is also introduced into existing purified gas distribution systems whenever those systems are disturbed, such as during maintenance or modification of the systems.
Conventional practice in the industry for eliminating such contamination is to run purified gas through the system until the output from the system is pure enough, e.g., until the moisture content and particulate level in the gas are low enough. This approach consumes large amounts of the purified gas in a wasteful manner until a steady state purified condition is reached. Such an approach is also time consuming, since it will often take considerable time, such as a matter of several days, before the steady state purified condition is reached. A need therefore exists for an improved apparatus and method for purifying such gas distribution systems.